Pharmaceutical companies Apotex and Novopharm had challenged Glaxo's 20-year-old AZT patent by claiming that the company had not conducted clinical trials on AZT's effectiveness in combating HIV infection when Glaxo applied for the patent. They also contended that Glaxo had "improperly" claimed credit for AZT's discovery. The court found that Glaxo had sufficient information about AZT and its anti-HIV activity to make a "sound prediction that it would be useful in the treatment of HIV disease and ruled that the patent is valid.

The court also ordered the two generic drugmakers to reimburse Glaxo nearly $200 million in lost revenue due to sales of their generic versions of the patented medication.

Glaxo faces similar lawsuits around the world challenging its patent on AZT, including one in the United States filed by the AIDS Healthcare Foundation that alleges the Glaxo patent is invalid because research into AZT's development was partially funded through federal tax dollars at the National Institutes of Health. "As someone who has a legitimate claim to this drug, I demand it be made available to patients worldwide," said Hiroaki Mitsuya, a member of the NIH team that discovered AZT, who supports the AIDS Healthcare Foundation's challenge of Glaxo's patent on the drug. "With 8,500 deaths a day to this dreaded disease, we have no time to waste."